5*5 PROCEEDINGS OP THE GEOLOGICAL SOCIETY. 



centralia, which manifestly favours the primitive duality of this 

 mesopodial (carpal, tarsal) element. 



Fig. 10. — Hind limb of Ichthyosaurus. (After Hawkins.) 



T, the tibia ; F, the fibula ; t, os tibiale ; /, os fibulare ; i, os intermedium • 

 c 1 , c 2 , ossa centralia. 



There remains for me to notice the scapula. In Ichthyosaurus 

 (fig. 1) its form is well understood. In Plesiosaurus Prof. R. Owen, 

 as has been already mentioned, believes that it has no dorsal exten- 

 sion answering to the blade in other Yertebrata ; but he finds such an 

 extension of the bone in Pliosaurus. I had thought that such 

 dorsal extension of the scapula was recognizable in skeletons of 



